In a wireless communication system, a base station refers to a device providing functions such as initial access, service transmission and resource management etc. to a terminal, and typically, the base station implements the above functions by channel control and message management. The base station communicates with the terminal through an uplink and downlink, wherein, the downlink refers to a wireless link from the base station to the terminal, and the uplink refers to a wireless link from the terminal to the base station.
The Orthogonal Frequency Division Multiplexing (OFDM for short) technology is a high speed transmission technology under a wireless environment, which enhances the performance of anti-multipath fading by expanding a pulse width of symbols. The implementation principle of the OFDM technology is that the high speed serial data is transformed into multi-path parallel data with a relatively low speed, and the multi-path parallel data are modulated onto sub-carriers which are orthogonal with each other for transmission. The Orthogonal Frequency Division Multiple Access (OFDMA for short) technology is to implement multiple access by enabling users to occupy different sub-carriers on the basis of the OFDM technology. In a wireless communication system using the OFDMA technology, the base station implements mapping of radio resources and allocation of radio resources. For example, the base station determines a system configuration and resource allocation information for the downlink transmission from the base station to the terminal and the system configuration and resource allocation information for the uplink transmission from the terminal to the base station and so on, the base station transmits the system configurations and resource allocation information to the terminal through a control channel, and the terminal receives these information on the determined control channel, and then receives and transmits data to communicate with the base station. In order to maintain timing synchronization when the base station communicates with the terminal, the base station needs to transmit a synchronization signal, which is referred to as a preamble or a preambl or a synchronization sequence in some communication standards, to the terminal in a downlink area.
In addition, in order to adapt various channel conditions, one kind of wireless communication system has multiple frame structures, and how to ensure consistence of the designs of control channels under a condition of multiple frame structures includes whether the locations and numbers of resources for transmitting the control channels are consistent; in the same generation of communication standards, multiple communication systems coexist, and how to design respective control channels to ensure that various communication systems can coexist is also very important; and in the process of the development of one communication system, a previous generation system thereof typically needs to be supported in the evolved system, for example, the IEEE 802.16m system is an evolved system for the IEEE 802.16e system, and the IEEE 802.16e is a previous generation system for the IEEE 802.16m, and therefore, supporting the previous generation system also limits the method for designing the control channels of the evolved system.
Another name of the Worldwide Interoperability for Microwave Access (Wimax) 16e is 802.16. Wimax 16e is an emerging broadband wireless access technology, and can provide an Internet oriented high speed connection. Wherein, IEEE 802.16e is a standard of the mobile broadband wireless access, and the Wimax 16e system refers to a communication system based on the IEEE 802.16e standard. The Wimax 16e communication system can be divided into two kinds of modes, i.e., a Partial Usage of Sub-Channel (PUSC) and a Full Usage of Sub-Channel (FUSC) according to a frequency band dividing mode. The PUSC refers to dividing the frequency bands into three sectors, and the FUSC refers to not dividing the frequency bands into sectors, and instead, combining the frequency bands for use. The resources of the Wimax 16e system can have multiple modes such as PUSC, FUSC, Adaptive Modulation and Coding (AMC) etc. in accordance with structures. Wherein, the AMC mode can have multiple modes, including a total of four structures occupying 1, 2, 3 and 6 symbols in time domain.
For the downlink part of the Wimax 16e system, there must be a preamble of one symbol and PUSC resources in units of 2 symbols, and this part of PUSC resources are used to transmit a system control signaling, and the remaining part can be comprised of one or more of various resource blocks such as PUSC, FUSC, AMC etc., i.e., the downlink resources must include a preamble and PUSC resources. For the uplink part, it is comprised of one or two of PUSC and AMC, i.e., the uplink can operate as long as there is one of PUSC and AMC.
The Long Term Evolution (LTE) project is a 3G evolution, and is dated from 3GPP conference in Toronto in 2004. The LTE is a transition between 3G and 4G, and is a global standard of 3.9G, which improves and enhances the air access technology of 3G, and uses OFDM and MIMO as the unique standard for the evolution of the wireless network thereof. The frame structure of the LTE communication system is comprised of data frames of 10 ms, wherein, each frame has 10 subframes, which can further be divided into two half frames of 5 ms, and each of which is comprised of a certain number of uplink symbols, downlink symbols or Guard Periods (GPs). A handover period can be divided into 5 ms and 10 ms according to uplink and downlink.
One frame structure for a 10 ms handover of the LTE communication system is shown in FIG. 1A, one frame with a time length of 10 ms (referred to as LTE frame herein) has one particular subframe S, where a Downlink Pilot Time Slot (DwPTS) is a downlink part in the particular subframe, and is used to transmit downlink symbols, and an Uplink Pilot Time Slot (UpPTS) is an uplink part in the particular subframe, and is used to transmit downlink signals, and a GP is a blank part in the particular subframe, which does not transmit any signal.
The structure of the configured frame for a handover period of 5 ms of the LTE communication system is shown in FIG. 1B, and the difference from the frame structure for the 10 ms handover is that there is one particular subframe S every time length of 5 ms, and there are two particular subframes S in one radio frame with a time length of 10 ms. In the present application, all downlink subframes and the DwPTS constitute the downlink area in the LTE frame, and all uplink subframes and the UpPTS constitute the uplink area of the LTE frame.
There are two kinds of OFDM symbols for the LTE system, one of which is a regular cyclic prefix and the other is a normal cyclic prefix, wherein, the lengths of the two symbols are different in time.
Both the Wimax 16e communication system and the LTE communication system can be divided into a Time Division Duplex (TDD for short) system and a Frequency Division Duplex (FDD for short) system. In the TDD system, for the wireless communication system based on OFDM or OFDMA, the mapping of radio resources thereof is primarily based on the frame structure and resource structure of the wireless communication system, and the frame structure describes the control structure of the radio resource in time domain, and the resource structure describes the control structure of the radio resource in frequency domain. The frame structure divides the radio resources into different levels of units in time domain, such as superframes, frames, subframes and symbols, and implements scheduling control by setting different control channels (such as broadcast channels, unicast and multicast channels etc.). Each superframe, frame, subframe and symbol occupy a certain time in time domain. In the TDD mode of the Wimax 16e communication system, as shown in FIG. 2, a frame length of one Wimax 16e frame is 5 ms, including a downlink area, an uplink area, an idle time period, which is referred to as a Transmission/Receive Transition Gap (TTG for short), between the downlink area and the uplink area, and an idle time period, which is referred to as a Receive/Transmission Transition Gap (RTG for short), between the uplink area and the downlink area. On the time slot of the TTG and the RTG, the terminal and the base station do not transmit any signal.
In the communication system, there may be a condition that the distance between central frequency points of the frequency bands used by two communication systems is rather near and the interval between two frequency bands is small or almost 0, and in such condition, there may be serious interference between the two communication systems, and the two communication systems in such condition are referred to as adjacent frequency communication systems. As shown in FIG. 3, the first communication system and the second communication system are two adjacent frequency communication systems, and the first communication system will produce energy leakage of the frequency band, and leaks a part of energy on the frequency band of the second communication system, which produces a large interference to the communication of the second communication system. Likewise, the second communication system will also produce interference to A. Especially when the second communication system performs uplink communication but the first communication system performs downlink communication at the same time, a terminal belonging to the second communication system will transmit uplink data to the base station, and at this time, a signal transmitted by the terminal of the second communication system will produce a large energy leakage of the frequency band and the energy is added to an antenna of a terminal of the first communication system, which produces a large interference to the reception of the downlink signal by the terminal of the first communication system, that is, the downlink signal of the first communication system and the uplink signal of the second communication system will interference the reception of the signal by the other party, vice versa. When considering adjacent frequency coexistence while two communication systems coexist (refers to the base stations of the two communication systems are located at the same place), the above interference problem will become more serious.